Intelligent discussion about line / in-breeding

[Carlton]

Of course, everything in the wild is random and more than likely it happens every now and then. What I'm talking about is deliberate in-breeding or line breeding to bring out certain traits. In the wild they are just trying to reproduce so their specie doesn't die off.

And, if a group of chams happens to become inbred due to geographic isolation and small gene pool, animals with a magnified weakness are quickly picked off by circumstance and predators. What concerns me with in-line or inbreeding in captivity is that animals who end up demonstrating a trait the breeder wants but who also carry an undesirable trait (for example sensitivity to certain diseases, poor immune system, tendency for MBD) DON'T get eliminated from the gene pool unless the breeder carefully documents any patterns in illness, poor development, longevity, etc. You could argue that captive animals don't need to be in prime physical condition to survive, but why sentence any captive animal to a shortened miserable life because of a breeding defect?

We may not be seeing all the physiological problems that are now common in dogs or cats, but we are working with many fewer generations than in a dog breed recognized for a hundred years or more. The day will come for chams eventually unless we are very careful. We may see that beautiful blue color without problems now, but eventually other problems will tag along.

I guess I don't agree that our current gene pool of any of the captive cham species is all that robust. The populations are pretty small and number of founders is also.

One other little comment and I will be quiet (not being an active breeder myself). Are grandparent and grandchild distant relatives? No way. They are one step removed from "immediate family" IMHO. A "distant" relative is something like a second cousin.

 

[sandrachameleon]

Quote:
Originally Posted by sandrachameleon
Ethical lines are generlly something that needs a group of people both involved and objective to hammer out, based on the collective views of the community.

That's why I thought this topic should be discussed

Fair enough. But you're unlikely to get truly objective input representing the collective views of the community (meaning more than just this forum community) on a chameleon forum full of dedicated chameleon keepers. We're a pretty small gene pool LOL
Still, interesting discussion

 

[Rocky]

Well one thing I'm wondering about it is the possibilities it could bring to the veiled chameleon industry. I think it's ridiculous how cheap they are these days. But I bet if certain traits were brough out through breeding (not necessarily all inbreeding or line breeding, but also through specific breeding) they could be completely turned around.

I saw something with the "All blue veiled" that is in development right now and I am very intrigued with the genetics that can be brought into this specie. Could you imagine to co dominant genes mixing in a veiled clutch. Kinda like a blue veiled with low end translucent, so it would be blue with white feet

Also, say you find a veiled with yellow bars then try to breed it to something with a high yellow body to try to eventually get a solid yellow chameleon.

Just thoughts though

 

[Brad Ramsey]

And, if a group of chams happens to become inbred due to geographic isolation and small gene pool, animals with a magnified weakness are quickly picked off by circumstance and predators.

Do you have some information/evidence to back up this statement?
Aren't most chameleon groups isolated? The chances of "getting busy" with your brother are pretty high.

I would suggest that this (inbreeding) happens a lot in nature with little effect, and that unrelated animals breed into the tree often enough to keep the gene pool strong.
I will agree that any animals born with defects or weakness, probably do not have much chance of survival, but I have suspicion (without evidence) that, that number is low.

-Brad

 

[stickytongue]

great info from the above sources but i would love to hear from people who have inbred or linebred yemen chameleons themselves

 

[zwhitman]

Carlton hit the nail on the head. The problem with line breeding is not the breeding itself, its the selection of offspring to become breeders! More on this in a moment.

First lets do a clarification of terms. Inbreeding refers to the breeding of very closely related animals, for several generations, causing problems in the offspring. It is a negative term for irresponsible breeding. Line breeding is the preferred term used by educated breeders who may occasionally breed related animals, but also introduce outside genetics to the line to keep it strong. IF line breeding is done correctly it can be done without any decrease in the health of the population. But you have to be very careful.

You also have to consider what a species is adapted to in the wild. Much of the scientific data we have about the dangers of inbreeding comes from laboratory bred mice. However mice are a fecund and widespread species that probably never evolved with closely related animals breeding on a regular basis. Certain reptiles may be very different. Take for example desert snakes from the southwestern US. Often you find small population hubs centered around a small piece of good habitat (a cliff face or stream bed for example) with many miles of poor habitat in between. These populations must be more able to deal with small gene pools or they would die out. They also must have some amount of gene flow between populations or they would evolve into different species or die out. I am not sure exactly where chams fall on this scale, but I would imagine there is a lot of species variability.

When you are considering captive populations you need to consider both the amount and the severity (for lack of better words). I.E. how closely related are the animals, and how many generations have they gone through without new gene introduction?

Breeding two closely related animals one time will not do anything bad unless you happen to be very unlucky and the parent animal is heterozygous for a dramatic genetic defect. This situation happens in nature all the time. As another person said, they don't know or care who their relatives are.

If you continue to only breed siblings (just an example) for many generations you will begin to see signs associated with inbreeding because you will increase the chances that individuals will carry multiple copies of a defective gene. These may be very subtle, like low hatch weight, or they may be dramatic birth defects.

So when and why do people do it? There are two different scenarios that are common and they are very different. Species like corn snakes and ball pythons have become popular due to the amount of mutations. These mutations are (usually) recessive which means that both parents must have the gene for the offspring to show the trait. This means that if you hatch out the first albino ball python ever, the ONLY way to get more of them is to breed it to its relatives. A good breeder will then out breed to maintain genetic diversity. But many people see the $$$$ and keep breeding closely related animals because it is the fastest way to get these traits without waiting for out breeding. No one would ever know until many generations later when the entire population has a problem. Specific diseases associated with morphs are known in many species.

Thankfully this is not the situation with chameleons. Chameleons are selectively bred for their colors over many generations (as opposed to a genetic mutation that appears suddenly). Therefore there is much less of a need to breed related animals. If you breed any two blue line panthers (related or not), the offspring have a good chance of being blue.

Coming full circle... the biggest issue is the selection of breeders. I don't care if you hatch out a panther that is bright yellow with purple polkadots, if its legs are wimpy and one eye is bigger than the other, DON"T BREED THAT ANIMAL!!!! And don't sell it to someone else with the intention of breeding it!

The reason inbreeding is less of a problem in the wild, is that if a breeding produces less fit animals, they will die off. In captivity it is up to us to ensure that the animals that go on to reproduce are fit. Those that are not can still make good pets but should not be bred. Select your hold backs by how well they feed and grow, not by the color of their skin, and you don't have to worry about mild line breeding to get pretty colors.

Stepping off soap box...